In a manufacturing facility engaged in mass production, air tools are often used on the assembly line. In operating an air tool over the course of a typical shift, a worker encounters substantial stresses and strains on muscles and ligaments of the hand and arm. This is particularly true for a rotating air tool, such as a screwdriver, a boltdriver, a nut socket, or a drill, which must be gripped tightly to resist both reaction torque of the tool and to provide the axial force necessary to insure tool engagement.
The stresses and strains increase worker fatigue. This can result in a loss of efficiency or a reduction in product quality. Worker injury can also result, which can lead to loss of work time and a need for a replacement worker, worker's compensation claims, and sometimes even liability for the employer.
The science of ergonomics or human engineering has attempted to answer many of the problems facing today's assembly line workers. Among the problems which have been confronted are those facing a worker operating a rotating tool. Deprag (Tradename) offers a air-powered screwdriver with what is described as an "ergonomic" handle. In cross-section, this handle has four lobes. More specifically, it has four slightly arcuate sides of substantially equal length, with rounded corners, so as to form one lobe at each corner.
The Deprag handle, however, is not truly ergonomic. The four lobed design does not closely fit a gripped hand, and the handle is somewhat difficult to grip over the course of an entire shift. In addition, the handle is an integral part of the tool, and cannot be removed. Thus, if the plastic grip is damaged or not desirable to a particular operator, there are no alternatives but to replace the relatively expensive motor housing/grip or force the operator to use a tool which is damaged or not comfortable to him.
It is clear that what is needed is a handle which is truly ergonomic, in the sense that muscle and ligament strain and fatigue is minimized. Such a handle should also be readily detachable so that the grip can be replaced or the tool can be operated without it, if desired by the operator.